Massive Himalayan gorge partly carved by Lake Erie-sized floods

Namcha Barwa, the highest mountain along the Tsangpo Gorge.

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The Grand Canyon may seem gobsmackingly enormous—because it is—but it is not without competition. The Yarlung-Tsangpo River flows eastward across the Tibetan Plateau before cutting south across the Himalayan Range and feeding into the mighty Brahmaputra River. Where it bends to the south, it runs through the Tsangpo Gorge. The river channel is only about 200 meters wide there (or roughly 656 feet), and the steep walls climb to truly awesome heights. At one point, the peaks on either side of the river rise more than 4,000 meters (nearly 2.5 miles) into the air—dwarfing the depth of the Grand Canyon.

This incredible incision is the result of the rapid growth of the Himalayas over the last 10 million years. With great uplift comes great erosion—as much as 5 to 10 millimeters (roughly .2 to .4 inches) of surface rock are removed each year across the region. That adds up in a hurry. Recent discoveries just upstream of the Tsangpo Gorge have revealed some fascinating details of its history, which featured giant floods that could do the work of thousands of years of erosion in a geological instant.

Last year, Ars reviewed a book written by University of Washington geomorphologist David R. Montgomery, who wrote about the mythology and geology of large-scale floods, in part from personal knowledge. In 2004, Montgomery and his colleagues reported their discovery of deposits left by lakes that formed in the Yarlung-Tsangpo River valley when the river was dammed by glaciers.